Slide projector with a device to facilitate replacement of the contact base lamp



Nov. 10, 1964 E. ZILLMER suns PROJECTOR WITH A DEVICE TO FACILITATE REPLACEMENT OF THE CONTACT BASE LAMP Filed Jan.

INVENTOR ERICH ZILLMER flna ATTORNEYS.

United States Patent 3,156,511 SLIDE PROJECTOR WITH A DEVICE TO FACILI- {QTE REPLACEMENT OF THE CONTACT BASE MP Erich Zillmer, Braunschweig, Germany, assignor to Voigtlander A.G., Braunschweig, Germany, a corporation of Germany Filed Jan. 3, 1962, Ser. No. 164,027 1 Claim. (Cl. 339-45) This invention relates to slide projectors and, more particularly, to novel means for facilitating the replacement of the lamp bulbs of projectors.

Certain types of projector lamp bulbs are provided with a dielectric contact base which has a dielectric or insulated locating pin and a pair of electrically conductive contact pins projecting therefrom. The locating pin projects with a relatively loose fit through a substantially central locating hole in a suitable socket mounted in the projector, as on the base of the latter, and the contact pins engage correspondingly located female connectors connected, through the usual control switch of the projector, to a. source of electric potential. The base of the lamp bulb also includes detent means, in the form of cams, which are cooperable with other detent means, in the form of grooves in resilient portions of the socket, to releasably lock the lamp bulb in the socket.

In order to replace a projector lamp bulb of this type, it is necessary to grip the bulb by hand and pull it axially out of the socket, and this requires considerable initial eifort to disengage the cooperating detent means on the lamp bulb base and on the socket. This is true for the reason that it is highly desirable to have a relatively tight fit between the lamp bulb base and the socket in order to properly restrain the lamp against vibration and accidental displacement. It is also usually somewhat difiicult to obtain an adequate grip on the lamp bulb for pulling it out of its socket, and a further hindrance to its removal is that the lamp bulb may frequently be hot to the touch. It frequently happens that, when the detent resistance is suddenly overcome, the lamp bulb may slip out of the insecure grip of the operator and break.

Slide projectors provided with what is known as a contact base actually facilitate the replacement of lamp bulbs. The relatively thick center guide or locating pin of the lamp bulb projects through the lamp socket and beyond the open bottom thereof when the lamp bulb is seated in the socket. Since only a relatively slight axial movement of the lamp bulb upwardly or outwardly is necessary to release the detent means, the lamp bulb can be readily loosened relative to its socket by pressure in an axial direction on the locating pin. Once the detent means are disengaged, the lamp bulb sets loosely in the socket and can be readily removed. It is a realization of this feature of contact base type of projectors which has led to the solution provided by the present invention.

In accordance with the invention, a novel releasing means is provided on the projector, which releasing means is accessible externally of the projector and acts on the base locating pin in such a manner as to displace it axially an amount sufiicient at least to release the interengaged detent means. Preferably, the releasing device takes the form of a lever so positioned and oriented that a relatively slight pressure on the accessible outer end of the lever is sufficient to move the lamp bulb outwardly of its socket a distance at least sufiicient to disengage the detent means.

Mechanisms of this general type have been used for a considerable period of time as ejectors of flash bulbs used with flash arrangements for cameras. However, in contrast to the type of arrangement used in ejecting flash 3,156,511 Patented Nov. 10, 1964 bulbs, the device of the present invention does not actually eject the lamp bulb but merely lifts it sufficiently to release the bulb so that its base remains in the socket although, due to the release of the detent means, it has a relatively loose fit therein. Once the detent means are disengaged, the lamp bulb can easily be lifted out of the socket by hand.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings. In the drawings:

FIG. 1 is a partial vertical sectional view through a slide projector, illustrating the projector lamp bulb, its socket, and one embodiment of the bulb release means of the present invention;

FIG. 2 is a view similar to FIG. 1 illustrating another embodiment of the release means;

FIG. 3 is a sectional view taken on the line II of FIG. 4; and

FIG. 4 is a partial bottom plan view of the projector housing shown in FIG. 2.

Referring first to FIG. 1, a so-called contact base lamp bulb 1 is illustrated as having a base 2 carrying detents or cams 3 cooperable with detents or grooves 4 of a socket 5 mounted on the base 6 of a slide projector housing 7. The base 2 of lamp bulb 1 is provided with a relatively heavy or large and elongated center guide or locating pin 8 arranged to extend somewhat loosely through a locating aperture in the socket 5 and into a relatively large recess or bore 9 opening downwardly through the base 6. It will thus be noted that pin 8 is readily accessible from beneath the base 6 of the projector housing 7.

In accordance with the present invention, a lever, having a relatively short arm 19 and a relatively longer arm 11, is pivoted about a horizontal axis 12 on the base 6. An ejector lug 13, in the form of a straight pin or of a curved end of the arm 19, is provided at the outer end of the shorter arm 10, while a manual grip 15 is provided at the outer end of the longer arm 11. Longer arm 11 and grip 15 project through a slot 14 in the wall of the projector housing 7. The ejector lug 13 loosely engages the end of the locating or guide pin 8 when the lamp bulb 1 is latched in the socket 5.

To remove lamp bulb 1 from socket 5, it is merely necessary to press lightly downwardly on the grip 15 of the lever 10, 11, as indicated by the arrow 21, and the resultant upward movement of the lug 13 will be sufiicient to move lamp bulb 1 axially upwardly an amount suifi cient for the cams 3 of the base 2 to disengage the detents 4 of the socket 5. Lamp bulb 1 is then seated loosely in socket 5, and can be easily removed therefrom by grasping it with the fingertips. The lever ratio can be set as desired by proper proportioning of the arms 10 and 11, with consideration being given to the effective resistance of the cooperating detent means.

In the embodiment of the invention shown in FIGS. 2, 3 and 4, a relatively elongated lever 16 is pivotal about a horizontal pin or axis 18 which, in turn, is pivotal in a plane parallel to the base 60 about a rivet or the like 17. Intermediate its ends, lever 16 carries a lug engageable with the locating pin 8 of the lamp bulb base 2. The free end of lever 16 projects outwardly beyond the lamp base and is formed with a grip whereby the lamp bulb may be released from its detent maintained engagement in the socket 2 by moving grip 150 upwardly in the direction indicated by the arrow 22.

In order that the lever 16 not interfere with the movement of positioning of the base 60 and projector housing 70, the lever may be swung parallel to the base 60 about the rivet or pin 1'7, as shown in FIG. 4 Such pivotal movement has an extent sufiicient to align lug 130 with an aperture 19 in the base 60 of the housing 70, and a leaf spring 20 biases lever 16 upwardly to maintain lug 130 engaged through aperture 19. The operative position of lever 16, as arranged for releasing a lamp bulb, is shown in solid lines in FIG. 4, whereas the inoperative position is shown in dot-and-dash lines.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

In a slide projector of the type having a socket receivin a projector lamp bulb having a contact base formed with a locating pin projecting through a locating opening in the socket and with detent means releasably interengageable with detent means on the socket to releasably latch the lamp bulb in the socket; means for releasing the interengaged detent means, to provide for replacement of the lamp bulb, comprising a lever pivoted to the projector base about an axis extending substantially parallel to the base and spaced substantially from said socket in a lateral direction, said lever having an operating end projecting laterally beyond the projector base for manual swinging of said lever toward said socket; said lever carrying projecting means engageable with the outer end of said locating pin to move the lamp bulb outwardly of the socket, upon such swinging of said lever toward the socket, an amount sufficient to disengage the detent means; the operating end of said lever projecting laterally beyond the projector being formed with a manual grip, said lever being pivoted at its inner end to the projector base and carrying a lug intermediate its ends constituting said projecting means; further means pivoting the inner end of said lever to said projector base for swinging movements substantially parallel to said projector base; and the projector base having an opening spaced arcuately from said locating pin for receiving said lug when said lever is swung laterally out of operative relation with said locating pin; and spring means biasing .said lever toward said projector base to engage said lug in said projector base opening and to retain said lever engaged with the undersurface of said projector base.

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